The Relationship Between Bone + Prostate Cancer

Dr. Shore is also a board member of the Bladder Cancer Advocacy Network and serves on the editorial boards of Urology Times, UroToday, PLOS One, and the World Journal of Urology.

He spoke with Prostatepedia about the relationship between bone and prostate cancer.

Dr. Shore: Prostate cancer, more than any other cancer, spreads to bone when metastases occur. Over 90% of men who die of prostate cancer will have bone mets, and we have a lot to learn about why that is. Various factors called cytokines or chemokines make the bone microenvironment, or the bone compartment, a fertile bed for the adenocarcinoma cells of the prostate cancer.

With prostate cancer, or any other cancer that spreads to the bones, there are sequelae from that progression. The involvement of bone from prostate cancer often causes pain that requires treatment.

However, pain is not the only consequence of bone metastasis. It can also lead to fractures and bone marrow suppression. This suppression affects the production of red and white blood cells and platelets, important factors in fighting cancer cells and protecting the body from infections.

If bone metastases involve areas of the spinal cord or other adjacent neural structures, there can be nerve impingement, a difficult and dangerous complication.

We want to be vigilant in understanding how to prevent spread to the bone, how to detect bone metastases, and how to recommend therapies that prevent complications.

Dr. Shore: Absolutely yes. We use the words “mainstay” or “foundational” for the role

of suppressing male testosterone or what we now regularly refer to as androgen deprivation therapy (ADT). When initiated, ADT puts the cancer cells in remission in more than 95% of cases. In addition to lowering the androgen (testosterone), ADT lowers dihydro- testosterone and estrogen levels.

Because ADT greatly reduces the hormones that are responsible for maintaining bone density, we’re putting the prostate cancer cells in remission, but we’re also having a negative effect on the strength of the bone, or bone mineralization. Bone demineralization is more profound in men than women who have post-menopausal bone demineralization. This can lead to fragility fractures due to the bone being weakened.

Though bone demineralization can result in complications, we have strategies to counteract it. The National Osteoporosis Foundation emphasizes the importance of looking at risk factors for bone demineralization, including family history, prior fractures, sedentary lifestyle, ADT, and patient age. Some factors are even country specific.

I use the Fracture Risk Assessment Tool (FRAX) 4 nomogram to help determine a patient’s risk for a fracture, especially after starting ADT.

Dr. Shore: We have many recommendations for patients. The first is to assess their risk. We also recommend that most patients begin vitamin D and calcium supplements once they start ADT. Patients should discuss their options with a physician

or learn about it online.

Regular exercise is incredibly important. There are many ongoing Phase III trials that are working to prove the importance of avoiding a sedentary lifestyle. It’s rather intuitive that maintaining a reasonable exercise program throughout life has a positive impact if you are diagnosed with prostate cancer, and if you’re on a drug such as an ADT, which puts you at risk for bone demineralization.

There are other side effects of ADT. Because we see loss of muscle, or sarcopenia, weight bearing exercise is also important. Bone demineralization combined with sarcopenia can lead to an increased risk of falls. If an elderly patient falls while on ADT, they run a high risk of having a fracture.

Bone fractures can impact your lifestyle, requiring further medical or even surgical intervention. These complications can add up and affect the cost of your healthcare. It is important to avoid a sedentary life, smoking, and excessive alcohol.

After getting a bone densitometry, or a dual-energy X-ray absorptiometry (DEXA) scan, you can take advantage of approved medications to help improve the bone density. One example is the monoclonal antibody Prolia (denosumab), which has been available for several years and is also approved for post-menopausal women at risk for osteoporosis or Prolia (denosumab) can be given subcutaneously one cc or one millimeter underneath the skin, every six months. It’s also approved for men with prostate cancer on ADT who are at significant risk of bone fracture.

Another option is the class of drugs known as bisphosphonates, which can be used to help improve bone density and prevent fractures.

Dr. Shore: Yes. These are all good things to do as you age, in general, or if you have the misfortune of getting a diagnosis of cancer, and particularly an aggressive cancer.

Now that many prostate cancer diagnoses can be carefully followed, the diagnosis of prostate cancer shouldn’t impact lifestyle. We want to be proactive in preventing complications of therapy, whether it’s ADT or other approved therapies, because they can all have a negative impact on bone.